Biomedical subjects

S He

Publications and source records attributed to S He.

At least 145 records · Page 8Linked to original sources

PubMed1999

[In vitro hepatic targeting tendency of galactosyl-anti CD3 McAb-TILS].

This study was undertaken to enhance the hepatic targeting tendency of tumor infiltrating lymphocytes (TILs) and hence to lower the recurrence rate of primary liver cancer after hepatectomy. Galactosyl-anti CD3McAb-TILs were prepared and then were incubated together with hepatocytes. Their interaction through asialoglycoprotein receptor-mediated mechanism was observed under the inverted phase contrast microscope. The carbohydrate density of galactosyl-anti CD3McAb and the combining rate of galactosyl-anti CD3McAb with TILs were measured. The results revealed that galactosyl-anti CD3 McAb-TIL obviously were adhered to hepatocytes. The carbohydrate density of galactosyl-anti CD3McAb was 62.18, and the combining rate of galactosyl-anti CD3McAb with TILs was 97.9%. The results suggested that in vitro hepatic targeting tendency of galactosyl-anti CD3McAb-TILs was satisfactory, and that the carbohydrate density of 62.18 and the combining rate of 97.9% ensured the effective use of TILs.

Animals↗

PubMed1999

[Species and distribution of Chinese medicinal plant Caesalpinia].

OBJECTIVE: To gain a clear idea on the resources of medicinal plant Caesalpinia in China. METHOD: Conducting field investigation and consulting related specimens and data. RESULT: The distribution, growing environment and medicinal parts of 14 species of Caesalpinia have been clarified, and a key for their identification is given. CONCLUSION: A scientific basis for further study of the medicinal plant Caesalpinia in China has been provided.

Caesalpinia↗

PubMed1999

[Investigation on the fruit output and ecological environment of Caesalpinia in China].

OBJECTIVE: To estimate the fruit output of Caesalpinia in China and understand its ecological environment. METHOD: On-the-spot investigation in the producing area. RESULT: The output of 8 species of Caesalpinia was estimated and their ecological environment was described. CONCLUSION: The natural resources of Chinese Caesalpinia, especially C. decapetala and C. minax, are rich, and thus worth exploring and developing.

Caesalpinia↗

PubMed1999

Effects of Tryptergium Wilfordii Polyglyco-sidium on the tumour necrosis factor levels in aqueous humor after intraocular lens implantation.

PURPOSE: Effects of Tryptergium Wilfordii Polyglyco-sidium (TWP) on the Tumour Necrosis Factor (TNF) levels in aqueous humor after intraocular lens (IOL) implantation were studied in rabbits. METHODS: Twenty-seven pigmented rabbits were divided into three groups. In the first group, the IOL were placed in the capsular bag after lens extraction. In the second group, rabbits received TWP therapy after IOL implantation. And in the third group, rabbit received prednisone therapy after IOL implantation. Aqueous humor samples were aspirated on the 1st, 3rd, 7th, and 14th postoperative day. A modified double antibodies indirect sandwich ELISA was used to detect for the presence of TNF. The data were closely studied by means of analysis of variance with SAS software. RESULTS: It was found that TNF level in aqueous humor reached its maximum on the 7th postoperative day in the group with IOL implantation. It was also found that the TNF levels in aqueous humor on the 7th and 14th postoperative day were significantly lower (P < 0.05) in the TWP-treated group with IOL implantation than those in the non-treatment group and the steroid-treated group. CONCLUSIONS: The current study offers evidence that TWP is more effective than the steroid in reducing the TNF level in aqueous humor after IOL implantation.

Animals↗

PubMed1999

[A Raman spectral studies of rare-earth (REE) fluoro-carbonate minerals].

The Raman spectra of REE fluoro-carbonate minerals were studies by a type of RIT-30 laser Raman spectrometer. On the basis of Raman spectral properties, REE fluoro-carbonate minerals can be divided into three groups: Ba-REE fluoro-carbonate mineral, Ca-REE fluoro-carbonate mineral and REE fluoro-carbonate mineral. Obviously, a differential kind of mineral is different in the vibration frequency of the Raman spectra. They are as follows: Cordylite v1-1 088, v2-967, v3-1 538, v4-720, 628; Hauheite v1-1 089,v3-1 525, 1 596, v4-720, 649; Cerbaite v1-1 088, v2-911, v3-1 516, v4-718,625; Parisite v1-1 095,1 075, v2-915, v3-1 461, v4-744, 732; Bastnesite v1-1 098, v2-835, v3-1 476, 1 447, v4-732.

English Abstract↗

PubMed1998

Identification of Glu-540 as the catalytic nucleophile of human beta-glucuronidase using electrospray mass spectrometry.

Human beta-glucuronidase is a member of the Family 2 glycosylhydrolases that cleaves beta-D-glucuronic acid residues from the nonreducing termini of glycosaminoglycans. The enzyme is shown to catalyze glycoside bond hydrolysis with net retention of anomeric configuration, presumably via a mechanism involving a covalent glucuronyl-enzyme intermediate. Incubation of human beta-glucuronidase with 2-deoxy-2-fluoro-beta-D-glucuronyl fluoride resulted in time-dependent inactivation of the enzyme through the accumulation of a covalent 2-deoxy-2-fluoro-alpha-D-glucuronyl-enzyme, as observed by electrospray mass spectrometry. Regeneration of the free enzyme by hydrolysis or transglycosylation and removal of excess inactivator demonstrated that the covalent intermediate was kinetically competent. Peptic digestion of the 2-deoxy-2-fluoro-alpha-D-glucuronyl-enzyme intermediate and subsequent analysis by liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry indicated the presence of a 2-deoxy-2-fluoro-alpha-D-glucuronyl peptide. Sequence determination of the labeled peptide by tandem mass spectrometry in the daughter ion scan mode permitted the identification of Glu-540 as the catalytic nucleophile within the sequence SEYGAET.

Affinity Labels↗

PubMed1998

Identification of Glu-120 as the catalytic nucleophile in Streptomyces lividans endoglucanase celB.

Streptomyces lividans CelB is a family-12 endoglucanase that hydrolyses cellulose with retention of anomeric configuration. A recent X-ray structure of the catalytic domain at 1.75 A resolution has led to the preliminary assignment of Glu-120 and Glu-203 as the catalytic nucleophile and general acid-base respectively [Sulzenbacher, Shareck, Morosoli, Dupont and Davies (1997) Biochemistry 36, 16032-16039]. The present study confirms the identity of the nucleophile by trapping the glycosyl-enzyme intermediate with the mechanism-based inactivator 2', 4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-cellobioside (2FDNPC). The kinetics of inactivation proceeded in a saturable fashion, yielding the parameters kinact=0.29+/-0.02 min-1 and Kinact=0.72+/-0.08 mM. Uncompetitive inhibition was observed at high concentrations of 2FDNPC (Ki=9+/-1 mM), a behaviour that was also observed with the substrate 2',4'-dinitrophenyl beta-D-cellobioside (kcat=40+/-1 s-1, Km=0.35+/-0.03 mM, Ki=24+/-4 mM). Protection against inactivation was afforded by the competitive inhibitor cellobiose. The electrospray ionization (ESI) mass spectrum of the intact labelled CelB indicated that the inactivator had labelled the enzyme stoichiometrically. Reactivation of the trapped intermediate occurred spontaneously (kH2O=0.0022 min-1) or via transglycosylation, with cellobiose acting as an acceptor ligand (kreact=0.024 min-1, Kreact=54 mM). Digestion of the labelled enzyme by pepsin followed by LC-ESI-tandem MS (MS-MS) operating in neutral loss mode identified a labelled, singly charged peptide of m/z 947.5 Da. Isolation of this peptide by HPLC and subsequent collision-induced fragmentation by ESI-MS-MS produced a daughter-ion spectrum that corresponded to a sequence (QTEIM) containing Glu-120. The nucleophile Glu-120 and the putative acid-base catalyst Glu-203 are conserved in all known family-12 sequences.

Amino Acid Sequence↗

PubMed1998

Close correlation between activity in brain area MT/V5 and the perception of a visual motion aftereffect.

Studies in primate physiology and human functional neuroimaging have convincingly shown that the area of the brain termed MT/V5(+)-which includes the middle temporal visual area MT/V5 along with adjacent motion-sensitive areas such as MST--is involved in the processing of motion information [1,2]. Tootell et al. [3] showed that the blood oxygenation level dependent (BOLD) signal measured by functional magnetic resonance imaging (fMRI) in the human MT/V5+ seemingly correlates with the strength of perceived motion aftereffect (MAE), the illusory motion of a stationary pattern that one sees after adapting to a moving pattern [4]. The signal in MT/V5+ decayed slowly during the period when the MAE was seen. It is possible that this slow decrease in MT/V5+ activity was unrelated to the perceptual experience of motion. After replicating Tootell et al.'s experiment, a modified version of the experiment was conducted in which a blank period was inserted between the adapting motion stimulus and the stationary testing pattern. The results demonstrated that MT/V5+ activity indeed decayed more slowly after an effective unidirectional motion adaptation than after bidirectional adaptation, without corresponding perception of MAE. Nevertheless, in a more conclusive experiment, we adapted observers to a unidirectional motion for a very long period and showed that the activity in MT/V5+ changed in synchrony with the presence and absence of perceived MAE, simply as a result of presenting a stationary visual stimulus in and out of the adapted retinal region.

Adaptation, Physiological↗

PubMed1998

Identification of glu-277 as the catalytic nucleophile of Thermoanaerobacterium saccharolyticum beta-xylosidase using electrospray MS.

Thermoanaerobacterium saccharolyticum beta-xylosidase is a member of family 39 of the glycosyl hydrolases. This grouping comprises both retaining beta-d-xylosidases and alpha-l-iduronidases. T. saccharolyticum beta-xylosidase catalyses the hydrolysis of short xylo-oligosaccharides into free xylose via a covalent xylosyl-enzyme intermediate. Incubation of T. saccharolyticum beta-xylosidase with 2,4-dinitrophenyl 2-deoxy-2-fluoro-beta-d-xyloside resulted in time-dependent inactivation of the enzyme (inactivation rate constant ki=0.089 min-1, dissociation constant for the inactivator Ki=65 microM) through the accumulation of a covalent 2-deoxy-2-fluoro-alpha-d-xylosyl-enzyme, as observed by electrospray MS. Removal of excess inactivator and regeneration of the free enzyme through transglycosylation with either xylobiose or thiobenzyl xyloside demonstrated that the covalent intermediate was kinetically competent. Peptic digestion of the 2-deoxy-2-fluoro-alpha-d-xylosyl-enzyme intermediate and subsequent analysis by electrospray ionization triple-quadrupole MS in the neutral-loss mode indicated the presence of a 2-deoxy-2-fluoro-alpha-d-xylosyl peptide. Sequence determination of the labelled peptide by tandem MS in the daughter-ion scan mode permitted the identification of Glu-277 (bold and underlined) as the catalytic nucleophile within the sequence IILNSHFPNLPFHITEY.

Amino Acid Sequence↗

PubMed1998

Two distinct forms of human mast cell chymase--differences in affinity for heparin and in distribution in skin, heart, and other tissues.

Chymase, a chymotrypsin-like protease secreted by human mast cells, is generally considered to be a single enzyme. However, by heparin-agarose chromatography of high-salt extracts of human skin, we have consistently resolved three peaks of chymotryptic activity, eluting at 0.4 M NaCl (peak A), 1.0-1.2 M NaCl (peak B) and 1.8-2.0 M NaCl (peak C), with peak B containing 75-90% of the recovered activity. Each peak retained its identity upon rechromatography. The three peaks of activity were similar in substrate specificity and inhibitor profile and distinctly different from other chymotryptic enzymes, including cathepsin G and the stratum corneum chymotryptic enzyme. Examination of different tissues revealed that peak C was virtually absent from synovial tissue, was present as a minor component in skin and heart, but constituted the predominant chymotryptic activity in lung. Peaks B and C from skin tissue were further purified by chromatography on Sephacryl S-200. Both had a molecular mass of 28-29 kDa, yielded the N-terminal sequence reported for chymase, and on western blots reacted with a panel of polyclonal, monoclonal and antipeptide antibodies against chymase. Chymase C required higher concentrations of NaCl to overcome the stimulatory effects of heparin than did chymase B, but had a similar pH profile. Thus, human chymase exists in at least two distinct but similar forms, and the differences in heparin binding and tissue distribution could have important consequences for enzyme function.

Chromatography, Affinity↗

PubMed1998

Mechanism of mitral regurgitation in hypertrophic cardiomyopathy: mismatch of posterior to anterior leaflet length and mobility.

BACKGROUND: In hypertrophic cardiomyopathy, a spectrum of mitral leaflet abnormalities has been related to the mechanism of mitral systolic anterior motion (SAM), which causes both subaortic obstruction and mitral regurgitation. In the individual patient, SAM and regurgitation vary in parallel; clinically, however, great interindividual differences in mitral regurgitation can occur for comparable degrees of SAM. We hypothesized that these differences relate to variations in posterior leaflet length and mobility, restricting its ability to follow the anterior leaflet (participate in SAM) and coapt effectively. METHODS AND RESULTS: Different mitral geometries produced surgically in porcine valves were studied in vitro. Comparable degrees of SAM resulted in more severe mitral regurgitation for geometries characterized by limited posterior leaflet excursion. Mitral geometry was also analyzed in 23 patients with hypertrophic cardiomyopathy by intraoperative transesophageal echocardiography. All had typical anterior leaflet SAM with significant outflow tract gradients but considerably more variable mitral regurgitation; therefore, regurgitation did not correlate with obstruction. In contrast, mitral regurgitation correlated inversely with the length over which the leaflets coapted (r= -0.89), the most severe regurgitation occurring with a visible gap. Regurgitation increased with increasing mismatch of anterior to posterior leaflet length (r=0.77) and decreasing posterior leaflet mobility (r= -0.79). CONCLUSIONS: SAM produces greater mitral regurgitation if the posterior leaflet is limited in its ability to move anteriorly, participate in SAM, and coapt effectively. This can explain interindividual differences in regurgitation for comparable degrees of SAM. Thus, the spectrum of leaflet length and mobility that affects subaortic obstruction also influences mitral regurgitation in patients with SAM.

Adult↗

PubMed1998

Retinal pigment epithelial cells secrete and respond to hepatocyte growth factor.

Hepatocyte growth factor (HGF) is normally expressed by mesenchymal cells while its receptor, c-Met, is expressed in epithelial cells. Since HGF is critically involved in epithelial-mesenchyme interactions and the retinal pigment epithelium (RPE) is present at the interface between the retina and choroid, this study was initiated to determine whether the RPE expresses or responds to HGF in vitro. Cultured adult and fetal human RPE expressed mRNA for HGF and c-Met by RT-PCR. ELISA assay demonstrated the secretion of HGF into RPE culture supernatants. Tyrosine phosphorylation of c-Met was constitutively found in 72 hour RPE cultures and could be rapidly induced in serum-starved cells by concentrated RPE supernatants. HGF was mitogenic for cultured RPE (100 ng/ml.) and stimulated their chemotaxis (maximal response at 50 ng/ml). RPE are one of only a very limited number of epithelia that express both HGF and its receptor, suggesting the possibility of an autocrine action for this growth factor.

Adult↗

PubMed1998

The induction of a prolonged increase in microvascular permeability by human mast cell chymase.

Chymase is a major constituent of the secretory granules of human mast cells, but little is known of the contribution of this serine proteinase in acute allergic reactions. We have purified chymase from human skin tissue, and have investigated its potential to induce microvascular leakage in vivo. Injection of chymase into the skin of guinea pigs provoked an increase in microvascular leakage within 20 min. Although skin reactions were smaller than those elicited with similar quantities of histamine at this time point, they were much longer-lived, and were still apparent 120 min following injection. Chymase induced microvascular leakage was reduced in the presence of soybean trypsin inhibitor, and abolished by heat inactivating the enzyme, indicating dependence on an intact catalytic site. Little evidence was found for synergistic interactions between chymase and either histamine or tryptase. Antihistamine pretreatment of animals did not reduce the magnitude of skin reactions to chymase suggesting that they were not mediated by histamine release. Chymase could contribute to increases in microvascular permeability following mast cell degranulation in allergic disease.

Animals↗

PubMed1998

Isoform-specific regulation of the Na+/Ca2+ exchanger in rat astrocytes and neurons by PKA.

The Na+/Ca2+ exchanger is a major transporter of Ca2+ in neurons and glial cells. The Na+/Ca2+ exchanger gene NCX1 expresses tissue-specific isoforms of the Na+/Ca2+ exchanger, and the isoforms have been examined here quantitatively using primary cultures of astrocytes and neurons. We present a PCR-based quantitative method, quantitative end-labeled reverse transcription-PCR (QERT-PCR), to determine the relative amounts of the NCX1 isoforms present in these cells. Six exons (A, B, C, D, E, and F) are alternatively spliced to produce the known NCX1 isoforms. Three exon B-containing isoforms (BDEF, BDF, and BD) are the predominant transcripts in primary rat cortical astrocytes and in C6 glioma cells. In contrast, exon A-containing isoforms (ADF and AD) are the predominant transcripts in primary rat hippocampal neurons. Functional differences between full-length constructs of NCX1 containing either the astrocyte isoform BD or the neuron isoform AD were examined in a Xenopus oocyte expression system. Although both isoforms function normally, the activity of the AD isoform can be increased 39% by activation of protein kinase A (PKA), whereas that of the BD isoform is not affected. We conclude that specific NCX1 isoforms are expressed in distinct patterns in astrocytes and neurons. Furthermore, the activity of a neuronal (but not glial) isoform of the Na+/Ca2+ exchanger can be altered by the activation of the PKA pathway.

Animals↗

PubMed1998

Induction of in vitro human macrophage anti-Mycobacterium tuberculosis activity: requirement for IFN-gamma and primed lymphocytes.

Mycobacterium tuberculosis (Mtb) is the world's leading infectious cause of mortality. Despite the overwhelming data supporting the critical role of cellular immunity, little is known of the early microbial and immune cell interactions and whether human macrophages can be activated to express anti-Mtb activity. We report the reconstitution of an in vitro system whereby human macrophages express anti-Mtb activity only in coculture with PBL and with IFN-gamma. Omission of IFN-gamma in the cocultures or Mtb lysate/IFN-gamma-primed lymphocytes was associated with high growth of Mtb, high IL-10 and IL-12 p40, nearly undetectable IL-12 p70 levels, and the highest percentages of CD4 and CD8 T cells. In contrast, IFN-gamma treatment of cocultures containing Mtb lysate/IFN-gamma-primed PBL reduced bacilli count by approximately 2.5 log, decreased the production of IL-10 by 5.7-fold, increased IL-12 p70 by approximately 50-fold, and reduced the percentages of CD4 and CD8 T cells. Activation of anti-Mtb activity was time and dose dependent. At 2000 U/ml of IFN-gamma, bactericidal activity was achieved (10-fold reduction from initial inoculum). Anti-Mtb activity against several strains of M. tuberculosis (H37Ra and H37Rv, and C, a clinical isolate) was observed and was associated with expression of inducible nitric oxide synthase. These data suggest that induction of human macrophage anti-Mtb activity required dual signaling from PBL and IFN-gamma. Thus, the development of an in vitro human system may greatly facilitate studies to delineate immune cells, cytokines, and effector functions/genes critical in controlling Mtb. Defining the mechanisms may also provide novel treatment strategies for tuberculosis.

Antigen Presentation↗

PubMed1998

In vitro stimulation of C1s proteolytic activities by C1s-presenting autoantibodies from patients with systemic lupus erythematosus.

Anti-C1s autoantibodies (IgG forms), which recognize the conjunction of C1s heavy chain and light chain (C1s-presenting autoantibodies) from patients with systemic lupus erythematosus (SLE), have been found to stimulate C1s enzymatic activities. This is due to acceleration of the proteolytic hydrolysis of the synthetic substrate C1-1 by C1s, enhancement of the complex formation of C1s with its natural pseudosubstrate, C1 inhibitor (C1 inh), and promotion of proteolytic activation of its natural substrate, C4. Seven of fifteen samples from patients with SLE were found to contain such autoantibodies. The hydrolysis of the synthetic substrate C1-1 catalyzed by C1s in 25 to 27 min in the presence of anti-C1s autoantibodies was equivalent to the hydrolysis of C1-1 catalyzed by C1s alone or C1s with control IgG from healthy sera in 110 min, approximately fourfold faster than the reaction in the absence of anti-C1s autoantibodies. Densitometry scanning data showed that the formation of the C1s-C1 inh complex in the presence of anti-C1s autoantibodies was three to four times greater than that with control IgG. It was also noticed that the autoantibodies convert almost all of the latent forms of C1s to an active form that binds to C1 inh. Another group of Western blots showed that C1s cleaved C4 alpha-chain three times faster in the presence of autoantibodies than of control IgG. It is likely that the overconsumption of complement components is common in the pathogenesis of tissue damage occurring in SLE.

Antigen-Antibody Complex↗

PubMed1998

Mitogen-activated protein kinase activation mediates PDGF-directed migration of RPE cells.

Growth factor-directed migration is a critical component of the wound healing response although little is known about the signaling pathways involved. We examined the effect of inhibiting the mitogen-activated protein kinase (MAPK) pathway on platelet-derived growth factor (PDGF) and fibronectin-induced cell migration of human retinal pigment epithelial (RPE) cells. Using transwell cell-culture chambers, the effect of PDGF-BB (10-50 ng/ml) and fibronectin on components of migration was measured with or without the MAPK pathway inhibitor PD98059 (10-30 microM) MAPK activation of serum-starved cells by PDGF-BB was demonstrated by an immunoprecipitation/kinase assay and by immunohistochemistry using antibody specific for phosphorylated MAPK. PDGF-BB (10 ng/ml) stimulated MAPK activity in RPE (10 min) and its nuclear localization (1 h). PD98059 inhibited the activation of MAPK by PDGF-BB or serum. PDGF-BB stimulated RPE chemokinesis, chemotaxis, and haptotaxis; chemokinesis was additively increased and chemotaxis synergistically increased by the presence of a fibronectin substratum. PD98059 potently inhibited fibronectin-induced haptotaxis and PDGF-BB-induced chemotaxis but inhibited chemokinesis only at higher PDGF-BB (50 ng/ml) concentrations in the presence of fibronectin substratum. These results demonstrate that MAPK is critically involved in multiple components of RPE migration in vitro and suggest the potential of targeting MAPK to inhibit RPE migration in vivo.

Becaplermin↗

PubMed1998

Leishmania lipophosphoglycan reduces monocyte transendothelial migration: modulation of cell adhesion molecules, intercellular junctional proteins, and chemoattractants.

We previously identified the structural requirement for the inhibitory activity of Leishmania lipophosphoglycan (LPG) to block endothelial adhesion to monocytes. Here we showed that LPG reduces transendothelial migration of monocytes. LPG pretreatment of endothelial cells (2 microM, 1 h) reduced monocyte migration across endothelial cells activated by bacterial endotoxin (LPS) or IL-1beta (60 and 46%, respectively). A fragment of LPG (i.e., repeating phosphodisaccharide (consisting of galactosyl-mannose)) and LPG coincubated with LPG-neutralizing mAb lacks inhibitory activity on monocyte migration. Pretreatment of monocytes with LPG (2 microM, 1 h) also did not affect monocyte migration through control or LPS-activated endothelial cells. FACS analysis reveals that LPG treatment blocked the LPS-mediated expression of E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 on endothelial cells and monocyte adhesion without altering the integrity of the endothelial monolayer. LPG (2 microM, 1 h) alone was capable of altering the expression and distribution of two junctional adhesion molecules, CD31 and vascular endothelium cadherin, as well as reversing the effects of LPS on these proteins. The induction of endothelial cells by LPS to transcribe and release monocyte chemoattractant protein-1 (MCP-1) was significantly reduced by LPG (40-65%). LPG treatment of nonactivated endothelial cells also suppressed by 55 to 75% the monocyte migration triggered by a MCP-1 chemoattractant gradient, and coincubation of LPG with neutralizing mAb abrogated the inhibitory activity. Together, these data point to a novel anti-inflammatory function of LPG in reducing monocyte migration across endothelial cells via a mechanism of inhibition of endothelial expression of cell adhesion molecules, modulation of intercellular junctional proteins, and synthesis of MCP-1.

Animals↗